Does turning down radiators preserve the heat in the water?

Air Source Heat Pumps (ASHPs)

Last Post by AllyFish 8 months ago

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Tufty

(@tufty)

Estimable Member Member

Joined: 3 years ago

Posts: 54

Topic starter 12/12/2024 3:29 pm

Hi all,

Sometimes - for no reason I can find - the rooms get uncomfortably warm, even though theres no change in outside temperature. My question is: If I turn down the radiator in the room Im currently in, will that preserve the heat in the water so it doesnt have to be heated os much when it goes round the house again? So - in effect - I havnt wasted any energy by turning the radiator down?

Thanks

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Toodles

(@toodles)

Illustrious Member Contributor

Joined: 3 years ago

Posts: 2033

12/12/2024 5:59 pm

In my opinion, the water that doesn’t flow through the radiator but wends its’ way along the flow, will be losing a small amount of energy from the surface of the pipework and the rest will be available to the flow input of the next emitter in the line.

One facet of balancing radiators is that when one emitter has its’ flow restricted, this makes more of the energy available to the next emitter and, as a result, more than one round of emitter tweaking is required via the lockshield valves.

As to whether you have ‘wasted’ any heat or energy, most internal pipes within the heated envelope of the house will be emitting some heat and being uninsulated, this contributes towards the overall heating. The emitters will (or should) be ensuring that the energy radiates or convects mainly from them but the pipework will contribute (or leak!) some energy - hopefully in useful areas. The return pipe run water will still have energy and the higher the temperature of this return flow, the less energy will be needed to return it to the desired flow temperature.

The Delta T (often designed to be 5 degrees C) is usually controlled by the heat pump adjusting flow speed and heat pump energy output, so the less energy that is needed, the lower the output needs to be from the pump; lowering flow temperature normally improves efficiency and reflects better COP figures. That’s my pennorth anyway! Regards, Toodles.

Toodles, he heats his home with cold draughts and cooks his food with magnets.

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AllyFish

(@allyfish)

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Joined: 3 years ago

Posts: 493

13/12/2024 9:37 am

South facing rooms with large windows can experience high solar gain. Is this the case? Solar gain is one factor that external weather compensated control cannot compensate for. Even in winter, the energy from the sun striking even double glazed windows can transmit high radiant heat energy into the room. Most ASHPs use an external air temperature sensor and control software to regulate heating supply temperature according to outdoor air temperature. If not solar gain, then it could be your heat emitters into the rooms prone to overheating need rebalancing to provide a little less output.

Some systems control heating capacity using indoor room temperature sensing, which is a slightly different method called load compensation, it's quite rare however as a control method, and is better suited to large open plan living single zone open spaces rather than traditional UK homes with multiple rooms.

For rooms with radiators that do get a little warm due to solar gain, TRVs can help, by setting them to a slightly higher temperature than you normally want to room to be, just to prevent it overheating.

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